Dragon theories

Theory 1: Where they are found

The Bermuda triangle is a scary place. They say that those who dare venture across, don't usually come back, alive. Why? 

My theory is, that a huge titan wing submaripper chases them away. Eats the ships and passengers. Why? 

Remember how only the Berkians (Hiccstrids family) could find the Hidden World? And that was because they were on dragons? I think that the dragons are protecting it. The submaripper would chase away any humans, unless they were family to the dragon riders. 

However there is a fault in this theory that luckily I have cleared up. Sometimes only a few go missing. Like the captain or crew. Or maybe just some passengers. I think a night fury or other quick dragon like the light fury or razorwhip, takes them. 

They grab them and drop them into the sea, far away from the ship or they eat them. One of the 2. 

Therefore, I think the Bermuda Triangle is where dragons can be found. Where, just like Hiccup said, they are waiting for the world to be ready for them to appear. Maybe they'll make another mistake and arrive too early? But with Toothless ad their leader, I highly doubt it. And besides, there will hopefully be another Hiccstrid that can save them all once again. And another Snotlout,  Fishlegs, Ruff, Tuff, Heather, Dagur, Alvin, Stoick, Valka, .... the list goes on!